The objectives of this study are: 1) To separate by ultrafiltration and gel-filtration chromotography urinary proteins from stone-forming, potential stone-forming and non-stone forming patients; 2) To characterize separate urinary proteins and calcium binding activity, effect on seeded crystal growth and immunologic activity in anti-stone matrix antibody; 3) To search for some reliable biochemical profile representative of stone forming and potential stone forming patients. Identification of specific urinary molecules and other urinary parameters in the urine of stone forming patients will enhance our knowledge of the process of stone initiation and growth and may have practical application providing guidelines to present crystal-matrix aggregation. Twenty-four hour urine specimens are collected for metabolic active non-infectious calcium oxalate/calcium phosphate stone forming patients and non-stone forming population. Urinary proteins and molecular weight 1,000-50,000 daltons are concentrated by ultrafiltration and separated by Sephadex column coromotography. Fractions are analyzed for calcium binding activity and effect on seeded crystal growth and immunologic reactivity to anti-stone matrix antibody. Individual investigations are revealed on the presence of increased calcium binding proteins in active calcium stone formers. These proteins are not increased in inactive stone formers or in uric acid or cystine stone formers. Studies are continuing to measure the effect of these proteins on seeded crystal growth.